L2metrics

- Added scripts for multi-lifetime evaluation
- Added validation for scenario info (complexity/difficulty)
- Added type hints
- Updated reference to metrics specification document 0.65
- Updated calculation for performance recovery to use negative slope
- Add docstrings
- Minor updates to example multi-task log

- Added validation to performance maintenance
- Updated performance maintenance calculation, more specifically maintenance values
- Updated backward transfer to compute multiple values for each task pair
- Updated example logs and documentation with ideal learner scenario
- Implemented option to compute transfer matrix with both contrast and ratio methods

- Added log validation
- Reformatted metrics report output
- Updated metrics calculations per metrics specification version 0.64
- Switched to Theil-Sen slope instead of linear regression for performance recovery
- Added parameter for selecting transfer calculation method (contrast vs ratio)
- Use median instead of mean for aggregating lifetime metrics
- Updated log data parsing per log format version 1.0
- Added flag for disabling smoothing
- Added flag for disabling plotting
- Added flag for disabling saving

- Updated initial metrics to include all major identified lifelong learning metrics
- Removed dependence on learnkit
- Refactored metrics calculations to integrate with different log format
- Updated workflow for storing single-task expert data
- Updated READMEs and example scripts
- Added new example logs along with their metrics outputs

- Updated initial agent and classification metrics for both adapting to new tasks and continual learning
- Updated reporting format, plots for metrics
- Added getting started with custom metrics guide (`examples/README.md`), including example log files (`examples/syllabus_ANT_harder-1582671493-285338/`), and example output plot (`examples/syllabus_ANT_harder-1582671493-285338_example.png`)

- Updated foundation code and initial metrics for continual learning
- Overview document of Metrics Framework (`docs/metrics_documentation.pdf`)